Question: Who is Carl Sagan's doctoral student?
Paraphrase: Who is Carl Sagan's doctoral student?
SPARQL (Wikidata):  select distinct ?obj where { wd:Q410 wdt:P185 ?obj . ?obj wdt:P31 wd:Q5 } 
Answer: James B. Pollack, Steven W. Squyres, Steven Soter, Owen Toon